The output side of the inverter is the PWM voltage waveform. After passing through the motor winding, the output current is approximately sinusoidal and lags behind the voltage by a phase angle, which is determined by the power factor of the motor. The output current of the inverter is detected by a precision resistor or a current transformer, and the current signal is processed by the CPU.
In order to protect the inverter, when the output current is higher than a certain threshold, the inverter will report an overcurrent fault. The drive also immediately blocks the pulse output. This is an important and necessary method to protect the drive components from damage. This fault cannot be blocked.
There are many reasons for the inverter overcurrent fault, which should be analyzed according to the actual situation. If you find the right source, and then the right medicine, you can generally solve it.
The motor cable is connected to the inverter and the motor. Then analyze from the inverter side and the motor side separately.
1. The first is the influence from the inverter side.
Common causes of inverter overcurrent on the inverter side are:
The acceleration time is too short. The greater the motor torque required at this time, the torque is proportional to the current, so the current is also large. Prolong the acceleration time appropriately.
Improve the function. If the voltage rises too high during the V/f control during startup, it may cause overcurrent. Appropriately reduce the voltage boost value.
The PID parameters are not suitable. Excessive dynamic response may cause overcurrent. Extend the filtering time, minus P plus I.
2, followed by the impact from the motor side.
Common causes of overcurrent in the inverter on the motor side are:
The motor cable is shorted to ground. The cable is not well insulated and has a broken skin. The cable insulation can be tested with a shaker to confirm the cable quality.
The motor is blocked. In this case, the inverter will try to use a larger torque to make the motor rotate, which may cause an overcurrent fault.
3. Finally, the hardware problem.
If the current detection mechanism inside the inverter is not working properly, or if there is a problem with the CPU processing mechanism, these are not solved by setting parameters, and need to be repaired.
If the inverter does not match the motor current, it may cause an overcurrent fault. For example, if a small inverter has a large motor, or if the nameplate parameters are wrong, it may cause an overcurrent fault.